The present invention relates generally to a method of making a hydroentangled nonwoven fabric with variable fiber density in selected patterns where the fabric is further laminated to a colored backing material such that the intensity of the color of the backing material on the laminate surface is controlled by fiber density in the patterned regions.
The production of conventional textile fabrics is known to be a complex, multi-step process. The production of fabrics from staple fibers begins with the carding process where the fibers are opened and aligned into a feed stock known as sliver. Several strands of sliver are then drawn multiple times on drawing frames to further align the fibers, blend, improve uniformity as well as reduce the diameter of the sliver. The drawn sliver is then fed into a roving frame to produce roving by further reducing its diameter as well as imparting a slight false twist. The roving is then fed into the spinning frame where it is spun into yarn. The yarns are next placed onto a winder where they are transferred into larger packages. The yarn is then ready to be used to create a fabric.
For a woven fabric, the yarns are designated for specific use as warp or fill yarns. The fill yarn packages (which run in the cross direction and are known as picks) are taken straight to the loom for weaving. The warp yarns (which run on in the machine direction and are known as ends) must be further processed. The packages of warp yarns are used to build a warp beam. Here the packages are placed onto a warper which feeds multiple yarn ends onto the beam in a parallel array. The warp beam yarns are then run through a slasher where a water soluble sizing is applied to the yarns to stiffen them and improve abrasion resistance during the remainder of the weaving or knitting process. The yarns are wound onto a loom beam as they exit the slasher, which is then mounted onto the back of the loom. Here the warp and fill yarns are interwoven or knitted in a complex process to produce yardages of cloth.
Coloring and shading are likewise complex processes in conventional textile production. Colors and patterns of color can be achieved by using yarns of various colors, resulting from the dyeing of the yarn packages themselves. Further, greige goods, yardage produced from undyed yarns, can be dyed in any of several ways common to the industry, such as jet dyeing, and vat dyeing. For application of color and patterns of colors onto the surface of a fabric, screen printing is commonly used, whereby pigments are applied to the fabrics by a series of engraved rolls where each roll applies a specific color and part of the pattern.
Detailed shading of colors, where more than one hue of a particular major color are apparent in the same fabric, is usually achieved with a yarn that has a blend of fibers, where each of the fibers takes up the color differently in the dyeing process. An example of such a yarn is heather yarns, popular for knitting sweaters.
In contrast, the production of nonwoven fabrics from staple fibers is known to be more efficient than traditional textile processes as the fabrics are produced directly from the carding process. Nonwoven fabrics are suitable for use in a wide variety of applications where the efficiency with which the fabrics can be manufactured provides a significant economic advantage for these fabrics versus traditional textiles. Hydroentangled fabrics have been developed with improved properties which are a result of the entanglement of the fibers or filaments in the fabric providing improved fabric integrity. U.S. Pat. No. 3,485,706, to Evans, hereby incorporated by reference, discloses processes for effecting hydroentanglement of nonwoven fabrics. More recently, hydroentanglement techniques have been developed which impart images or patterns to the entangled fabric by effecting hydroentanglement on three-dimensional image transfer devices. Such three-dimensional image transfer devices are disclosed in U.S. Pat. No. 5,098,764, hereby incorporated by reference, with the use of such image transfer devices being desirable for providing a fabric with enhanced physical properties as well as an aesthetically pleasing appearance.
It is a further aspect of this patterning technology that the density of the fiber population can be varied within specific areas of the pattern, such that a fiber rich region may appear as a raised portion and is adjacent to a comparatively fiber poor, densified region. It is this control over fiber placement that gives rise to the fabrics of this invention.
In the present invention, a hydroentangled and patterned fibrous material is laminated to a backing material which has a color that is in contrast to and usually of a deeper hue than any color in the patterned fabric. The backing material may be one of several types of materials able to provide a suitable color, such as films, foams and fibrous fabrics. The backing material may be attached by any means known in the industry for laminating to create a composite fabric, such as adhesive bonding, thermal bonding, and ultrasonic bonding or extrusion coating. It is a preferred embodiment of the present invention to use water jets for consolidating the composite when the backing material is a fibrous nonwoven. It is a further preferred embodiment of the present invention to use extrusion coating to consolidate the composite when the backing material is a primarily non-fibrous material, such as a film or foam. It is a less preferred embodiment of this invention to use adhesive bonding when the backing material is a film or foam.
It is an aspect of the present invention that the most preferred methods of consolidating the composite structure result in an intermingling of the two layers at the interface. In fact, there is a relocation of the fibers of a fibrous backing material into the facing layer fiber matrix as a result of the water jets used to consolidate the two layers. In the case of the non-fibrous, polymeric backing layers, the extrusion coating process results in the intrusion of a portion of the extruded backing material into the interstices of the fiber matrix of the facing layer.
Due to the variable thickness and density of the fibers in the patterned areas of the imaged fabric, the perception of the color of the backing material is distinct in different areas of the pattern as viewed from the patterned side of the facing fabric. In this manner, a highly decorative fabric is produced, whereby the patterned image is aesthetically enhanced by the variable hues of color associated with particular areas of the pattern.
A method of making a variably colored, nonwoven based composite material embodying the principles of the present invention contemplates the use of staple length fibers to facilitate economical fabric formation. Formation of the fibrous nonwoven fabric on a three-dimensional, image transfer device by hydroentangling imparts desired physical properties to the fabric such as the controlled placement of the fiber population relative to the desired three-dimensional pattern imparted by the imaging device. This facing fabric may be white or colored. The addition of highly colored backing materials, such as nonwoven fabrics, films or foams, results in a variable appearance of the color through the hydroentangled, patterned face fabric. In this manner, the pattern is enhanced by the creation of variations in color intensity and hue in selected regions of the pattern.
A method of making a nonwoven fabric in accordance with the present invention includes providing a precursor web comprising staple length fibers, continuous filaments or blends of staple length fibers and continuous filaments. The precursor web is preferably pre-entangled on a foraminous forming surface, preferably through the use of high-pressure water jets.
The present method further entails the provision of a three-dimensional, image transfer device having an array of three-dimensional surface elements thereon. The precursor web is positioned on the image transfer device, and hydroentangled to form an imaged nonwoven fabric.
The present invention further contemplates the addition of a colored backing material to the patterned nonwoven fabric by means known in the art. Suitable backing materials include fibrous webs, films and foams. These materials are colored by any means known in the art, such as screen printing, the use of chemical dyes or the extrusion of a film or foam containing pigments.